Inclusion Criteria:
* Age 50 years and older or 18-49 with 1 or more chronic high-risk medical conditions, and/or immunosuppression: chronic respiratory disease (including COPD, cystic fibrosis and asthma requiring at least daily use of preventative and/or reliever medication); chronic heart or vascular disease; chronic kidney disease; chronic liver disease; chronic neurological disease (including dementia, stroke, epilepsy); severe and profound learning disability; Down's syndrome; diabetes (Type 1 or Type 2); immunosuppression: primary (e.g. inherited immune disorders resulting from genetic mutations) or secondary due to disease or treatment (e.g. sickle cell, HIV, cancer, chemotherapy); solid organ, bone marrow and stem cell transplant recipients; morbid obesity (BMI \>35); severe mental illness; care home resident.
* Confirmed SARS-CoV-2 by nucleic acid testing or rapid antigen testing with proof of a positive test provided via a picture of the result
* Able to be enrolled and begin the study therapeutic within 5 days of onset of symptoms associated with SARS-CoV-2 infection
Exclusion Criteria:
* Admitted to hospital or in an ED for more than 24 hours
* Previously randomized to CanTreatCOVID
* Currently participating in a clinical trial of a therapeutic agent for acute SARS-CoV-2 infection that is not/suspected not compatible with the study therapeutics
* Already taking a study therapeutic or contraindication to a study therapeutic
* Inability for participant or caregiver to provide informed consent
Paxlovid Exclusion Criteria include:
* History of clinically significant hypersensitivity to the active substances in Paxlovid™ (nirmatrelvir /ritonavir) or to any of its excipients.
* Patients with known rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption.
* Patients with known current severe liver impairment (characterized by severe ascites, encephalopathy, jaundice, or prolonged INR. People with liver disease without any of these features are eligible).
* Is a recipient of a solid organ transplant and taking immunosuppressant medications.
* Patients with known moderate or severe renal disease (defined as CKD stage 3, 4 or 5 or current acute kidney injury or most recent eGFR in the past 6 months \<60 ml/min).
* Currently taking Paxlovid™.
* Clinical requirement to continue taking a drug which is contraindicated or not recommended for administration with Paxlovid™ in the context of CanTreatCOVID or is taking a drug which in the opinion of the investigator would put the subject at unacceptable risk.
* Has a known or suspected pregnancy.
* Is breastfeeding.
* Is of childbearing potential and is not willing to use a highly effective contraceptive
Antioxidant Exclusion Criteria include:
* Has a known or suspected pregnancy.
* Is breastfeeding.
* Is of childbearing potential and is not willing to use a highly effective contraceptive.
* Has allergy or intolerance to selenium, zinc, lycopene, vitamin C, ascorbyl palmitate, hypromellose, microcrystalline cellulose, or sodium stearyl fumarate
* Is taking warfarin as a preventive measure.
* Has advanced chronic kidney disease (CKD stage 3: eGFR ≥30 to \<60 mL/min, and severe renal impairment (eGFR \<30 ml/min, CKD stage 4-5)
* Has liver disease awaiting transplantation.
* Has a history of calcium oxalate kidney stones.
* Has a diagnosis of head and neck cancer within the past 5 years
* Has medical history of non-melanoma skin cancer
* Is taking selenium (≥300ug/day), zinc (≥40mg/day), lycopene (≥45mg/day), and vitamin C (≥1500mg/day) supplements at baseline
* Is consuming omega-3 fatty acids at baseline and is unwilling to stop during the intervention period.
